This article covers the prevention of damage to a bullet
casting mold, their care, and proper use. I received a damaged two cavity
Hensley & Gibbs Mold #50 as a result of an eBay auction in October
2006. To my disappointment, a previous owner had ruined the mold by
attempting to add additional venting to the mold cavities, and by allowing the
mold to become further damaged in a critical area, the projectile base (the
base had a sharp nick in the metal which was reproduced in the as cast bullet
as a notch).

Modifications of this type (the additional of supplemental
venting) are often a fatal cure to a disease known as improper bullet
fillout. The symptoms are rounded corners on the as cast bullet in areas
that have a right angle or corner. As every caster eventually learns,
good bullets have nice sharp corners when you are in the casting “zone” .

The correct cure for improper bullet fillout is to adjust
mold temperature, alloy mix, or alloy temperature. Rarely should the
owner attempt to correct this condition by altering the mold itself. It
has been posted numerous times, in numerous ways, by innumerable casters, that
molds sometimes display a “personality” and require additional care to discover
their preferences for temperature and alloy mix. The devoted caster
should carefully adjust those variables other than the mold in an attempt to
cure the problem. I own a 4 cavity Hensley & Gibbs bullet mold that
for some unknown reason, will not cast perfect bullets until I allow it to heat
up to the point where bullets are uniformly frosted in appearance, and then
allow it to cool gradually back to the good casting “zone”. Once it
cools, it will cast perfect bullet after perfect bullet for hours or as long as
my arms hold out. Other Hensley & Gibbs molds I own do not require
this overheating to work properly. It’s a mystery to me why this method
is required for this mold, but I learned about it by reading other casters
experience on the Internet.

As you can see in photo 1 &2 (click on the photo for a
larger version) the addition of crudely scratched vent lines is evident on the
mold face. Photo 2 shows damage to the bullet base area under the sprue
plate. Photo 3 shows the matching notch in the cast bullet created by the
nick in the mold base.

Age of the mold does not factor into the damage. Care
and use of the mold is the indicator of its current condition. If you
carefully use the mold during your stewardship (aren’t we all stewards of these
fine molds?) then you can pass on to other casters of a future generation as
fine an instrument as you used.